silly to re-install the old springs? Another key question - is the ride height equally off all around the car? Has one spring sunk more than the others or are they all the same? Often the suspension seems to take more of a beating on the passenger side due to road "crowning" issues ...
Lastly - with 174k on the springs, I'm make sure none have deep rusting issues that could cause a failure. Might be fine too - but worth checking while all is apart...